Freeman Dyson is a physicist who has been teaching at the Institute for Advanced Study in Princeton since Albert Einstein was there. When Einstein died in 1955, there was an opening for the title of most brilliant physicist on the planet. Dyson has filled it.

So when the global-warming movement came along, a lot of people wondered why he didnt come along with it. The reason hes a skeptic is simple, the 89-year-old Dyson said when I phoned him.

I think any good scientist ought to be a skeptic, Dyson said.

------------------------------------------------------

Dyson said his skepticism about those computer models was borne out by recent reports of a study by Ed Hawkins of the University of Reading in Great Britain that showed global temperatures were flat between 2000 and 2010  even though we humans poured record amounts of CO2 into the atmosphere during that decade.

That was vindication for a man who was termed a civil heretic in a New York Times Magazine article on his contrarian views. Dyson embraces that label, with its implication that what he opposes is a religious movement. So does his fellow Princeton physicist and fellow skeptic, William Happer.

There are people who just need a cause thats bigger than themselves, said Happer. Then they can feel virtuous and say other people are not virtuous.

When Einstein died in 1955, there was an opening for the title of most brilliant physicist on the planet. Dyson has filled it. So when the global-warming movement came along, a lot of people wondered why he didnt come along with it.

Uh, Paul? Did you forget about your first two sentences when you write the third? Seems like asked and answered to me.

3
posted on 04/05/2013 10:49:07 PM PDT
by Still Thinking
(Freedom is NOT a loophole!)

Of course. CO2 is plant food, and they can’t get enough of it. If you increase the amount of CO2 they have access to, plants grow faster, and in growing, extract more CO2 from their environment to be stored in their cells. So, it’s a feedback loop that is one of the things that prevents a “runaway” greenhouse effect from happening on Earth.

Another feedback loop is the oceans. If the temperature were to rise enough for the glaciers to melt and raise the sea level, it would increase the volume and temperature of the oceans, both of which are factors that would increase the amount of CO2 that would dissolve in the oceans, and be taken out of the atmosphere.

There is a nice short interview with Dyson at the link. He's pretty sharp for 89. He discusses how the basic science of CO2 flux in and out of vegetation has been ignored while the big money went to computer modeling.

I wish Dyson's friend and colleague Richard Feynman was still around to back him up.

I agree with everything you wrote with the following caveat: the oceans may be critical to the absorption of CO2 regardless of the ocean levels, in particular the phytoplankton - the single-cell plants that provide the foundation of the ocean food chain. If the rise in ocean temperatures or fall in salinity due to glacial melting starts to kill off the phytoplankton, a big part of the planet’s ability to absorb CO2 goes away. On the other hand, if the rise in temperatures promotes growth in the phytoplankton population, happy days are here again. Who knows?

Solubility of gasses in water generally decreases with increasing temperatures, which is why bubbles form in pots of water being boiled, that aren’t boiling yet. (Those are the air coming out of solution.) There are some exceptions but I don’t think CO2 is one of them. That said, I am not an alarmist.

17
posted on 04/06/2013 5:29:42 AM PDT
by coloradan
(The US has become a banana republic, except without the bananas - or the republic.)

Assuming that it were large enough to hold Mercury, Venus and Earth (and the Moon), I'd think it'd require the raw materials found in all the outer planets and the asteroid belt, and then some. Building a Ringworld would probably be easier.

Actually, for anyone interested in the subject, there was a ST:TNG novel called "The Dyson Sphere", which was okay reading, but had an appendix, which was about 1/4 or 1/3 of the book about the science of such a thing. (I have to admit that I didn't read too much of that either because it was a little dry or little over my head or both.)

That was vindication for a man who was termed a civil heretic in a New York Times Magazine article on his contrarian views. Dyson embraces that label, with its implication that what he opposes is a religious movement. So does his fellow Princeton physicist and fellow skeptic, William Happer. There are people who just need a cause thats bigger than themselves, said Happer. Then they can feel virtuous and say other people are not virtuous.

Not to be pedantic, but it's what they call a "reverse feedback loop."

Silly me, forty years of engineering we call them "negative feedback" loops. When you write out the differential equations defining a servo loop, the feedback term should be negative if the loop is to be stable.

Positive feedback can be at best "metastable", balance a pencil on it's point, it will stand straight up until the slightest disturbance causes it's center of gravity to move slightly out of vertical alignment with the contact point. This applies a small torque increasing the magnitude of the disturbance which continues to increase as the pencil falls over. (positive feedback)

Negative feedback may be illustrated by dropping a marble into a spherical bowl. The marble will roll "downhill" into the bottom of the bowl. It will probably over shoot and roll past the bottom and up the side some but then it reverses course and rolls back down until it finally comes to a stop at the lowest point. This oscillation about the rest position is typical of a negative feedback system w/o a damping term. If you tried the experiment with various liquids filling the bowl, you would find that water has little effect, light cooking oil has more of an effect, and honey will prevent the marble from overshooting the rest position completely. The viscous drag of the liquids provides a "damping" effect the will slow the marbels's travel and cause it to stop at a stable position. Critical damping is achieved when the moving marble reaches it's rest position in the least time with out overshooting. A little less damping will allow a small overshoot and a few oscillations (under damped). A little more damping will increase the time it takes for the marble to arrive at it's rest position (over damped).

Most positioning servos system are intentionally designed to be slightly under damped as the minor oscillations near setpoint improve repeatability by reducing hysteresis.

Regards, GtG

25
posted on 04/06/2013 11:16:05 AM PDT
by Gandalf_The_Gray
(I live in my own little world, I like it 'cuz they know me here.)

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